Interactive Wright 1901 Wind Tunnel

Glenn
Research
Center

We present here a Java applet derived from
FoilSim
which simulates the operation of the Wright 1901 Wind Tunnel.
There are two versions of this applet. This version
requires the user to manually record data and plot results in the same way
that the Wright brothers acquired their data. A more
modern version
records and reduces the data and produces plots
within the program.

This page shows an interactive Java applet which allows you to choose
one of the Wright Brother's 1901 wind tunnel models and
determine the lift or drag coefficient.
You can set the angle of attack, then turn the tunnel on and note the
angle formed on the dial.
You then use one of two forms to record and reduce your data to determine
the wing performance.

You can download your own copy of this applet by pushing the following button:

The program is downloaded in .zip format. You must save the file to disk and
then "Extract" the files. Click on "Tunl.html" or
"Foil.html" to run the program off-line. "Tunl.html" includes this tutorial,
"Foil.html" runs the program alone

Problems may occur while
running the applet due to it being outdated. Until it is updated, we have provided links describing
the tests and results for the Wright 1901 wind tunnel:TestsResults

This simulation works exactly the same way that the Wright Brother's
1901 wind tunnel
worked. The layout of the simulator shows an overhead view into the tunnel test section
at the upper left. You can choose to test the wing model on either the
lift balance
or the
drag balance
by clicking on the appropriate label in the view window at the upper left.
Clicking
on the words "Wind Tunnel", "Lift Balance", or "Drag Balance"
will also display pictures of the actual
machines. In the upper middle part of the simulator is the output dial. This
dial is the only output from the program.
For the lift balance, the dial gives the angle between
the brackets holding the model and the reference drag plates. The
sine
of this
angle is the major portion of the lift coefficient used in the
lift equation
as understood by the Wright Brothers.
For the drag balance, the dial gives the angle which the
model is deflected by the flow through the tunnel. The
tangent
of this angle plus the angle of attack gives the drag coefficient
used in the
drag equation divided by
the lift coefficient.
To the right of the output dial are the sequence buttons which take you through
the operation of the tunnel. The white button is the current operation, and you
must push the red/white buttons before doing the procedure.

Most of the procedures to operate the
lift balance
and the
drag balance
are the same. But the differences are noted in these instructions:

"Step 1. Select Model"
Choose between the lift balance and the drag balance by clicking on
the word on the schematic.
The yellow label is the balance selected.
Select the model to be tested by clicking on a blue and white drawing
at the lower left or lower right of the program.
There are 30 different models which you can choose from and we have put them
into three groups. You select the group by using the blue buttons
below the output dial.
The current selection has a
white background. When the selection is made, a photo of the actual model
used by the Wrights is shown at the lower center of the program and the
number of the model is displayed on the schematic.

"Step 2. Set Angle of Attack"
Set the angle of attack of the model.
You can set the angle by typing into the input box and hitting "Return" to
send the information to the program. Or, you can move the trailing edge of
the airfoil by using your mouse on the "hand" in the schematic.

"Step 3. Start the Tunnel"
Clicking this button causes
air to move through the tunnel., You will see the balance
and the output dial slowly deflect.
Wait until the dial quits moving before taking data.

"Step 4. Adjust for Drag"
For the lift balance, the upper cross beam must be moved to eliminate
the drag of the model from the measurement.
Clicking on this button will cause Wilbur's arm to enter the tunnel
and make the adjustment.
The resulting angle on the lift dial relates the lift of the airfoil to the
drag of the reference flat plates.
You don't have to make any adjustment for the drag balance.

"Step 5. Record Data"
Record your data on the appropriate data form. You can get a copy of the lift form
by pushing the "Lift Data Form" button and using your browser's "Print" command
to get a hard copy. Use the "Back" button to return here.
The data form has boxes for you to record the lift of two different
models so that you can compare their lift.
The drag data form can likewise be obtained by pushing the "Drag Data Form"
button.

"Step 6. Reduce Data"
You will have to do some additional math on the raw data to obtain the
lift and drag coefficients. Engineers call this reducing the data.
For the lift balance, you calculate the lift coefficient by using the formula
on the data form. You will need the area of the model which is
given on the model drawing. Since you also need the sine of the output dial angle,
we have included a table of sin(angle) which you can display
by pushing the "Table of sin(a)" button and using your browser's "Print" command
to get a hard copy. Use the "Back" button to return here.
For the drag balance, you calculate the drag coefficient by using the formula
given on the data form. You will need to record the angle of attack and
to compute the tangent of the output angle. You can obtain a table of
tan(angle) by pushing the "Table of tan(a)" button.
You can compare cases by graphing the results of your tests using graph
paper. Push the "Graph Paper" button and use your browser's "Print" command
to get a sheet of graph paper.

The brothers selected the shape of the models
to study the various design variables which affect wing performance.
They would run a series of tests
which would isolate the effect of a given design variable.
We suggest that you visit the
models page
and duplicate the conditions yourself.
The wing design of the 1902 glider
was never actually tested, but was based on models 9, 12 and 35.

NOTICE: In this simple program we are using a very simplified
analysis to compute the lift. We have applied some correction factors
to account for the wing
stall
which occurs at high angles of attack. If you compare the results of
this program with actual data from the Wright experiments of 1901, you will
notice some numerical differences, but we have tried to properly model
the trends of the data.
Similarly, we have made rather simple curve fits of the brothers' drag
data. You will notice numerical differences, but the trends are correct.